All black face cards are removed from a pack of playing cards. The remaining cards are well shuffled and then two cards are drawn at random one after the other without replacement. Find the probability that the first card is black and the second one is red?

All black face cards are removed from a pack of playing cards. The remaining cards are well shuffled and then two cards are drawn at random one after the other without replacement. Find the probability that the first card is black and the second one is red?

In a chess competition involving some boys and girls of a school, every student had to play exactly one game with every other student. It was found that in 45 games both the players were girls, and in 190 games both were boys. The number of games in which one player was a boy and the other was a girl is

In a chess competition involving some boys and girls of a school, every student had to play exactly one game with every other student. It was found that in 45 games both the players were girls, and in 190 games both were boys. The number of games in which one player was a boy and the other was a girl is